1. Field of the Invention
This invention relates to the structure of electrical connectors provided on a camera body, an interchangeable lens and accessories for the electrical connection thereof.
2. Related Background Art
In an interchangeable lens type camera system using a rotation mounting and dismounting type bayonet mount for coupling or separating a camera body, an interchangeable lens and accessories by clockwisely or counter-clockwisely rotating the mounts thereof, there are provided electrical connectors having electric circuits, respectively, and adapted to effect the giving and receiving of various kinds of information such as information for automatic exposure control and information for automatic focus adjustment, and having a number of contacts near the mounts.
FIG. 1 of the accompanying drawings shows an electrical connector for a camera according to the prior art. For example, Japanese Utility Model Publication No. 4-10582 discloses the electrical connector for a camera.
The reference numeral 1 designates an interchangeable lens, the reference character 1a denotes a lens side bayonet mount, the reference numeral 2 designates a camera body, and the reference character 2a denotes a camera side bayonet mount.
The reference numeral 3 designates the upper contact holding member of a lens side electrical connector which is formed of plastic.
The reference numeral 4 denotes a lower contact holding member which is also formed of plastics.
The reference numeral 5 designates a required number of contact springs.
The reference numeral 6 denotes a lens side flexible print distributing panel (hereinafter referred to as FPC) having a conducting pattern (not shown) provided on the surface of contact thereof with the contact springs.
The contact springs 5 and lens side FPC 6 are superposed one upon the other and are sandwiched by and between the upper contact holding member 3 and the lower contact holding member 4, and ultrasonic vibration is imparted thereto to thereby heat and weld the surfaces of contact between the upper contact holding member 3 and the lower contact holding member 4.
Rearwardly of the camera side bayonet mount 2a, a camera side contact holding member 7 formed of plastic is secured to the inner peripheral surface of the camera body 2. A contact 8 is insert-formed in the camera side contact holding member 7, and a camera side FPC 9 is soldered to the contact 8.
In such a lens side electrical connector, the spring force of the contact springs 5 always acts to keep the upper contact holding member 3 and the lower contact holding member 4 away from each other and therefore, where a plurality of contact springs 5 are provided in the circumferential direction, their combined spring force acts, and if the number of the contact springs 5 becomes great, the spring force thereof will exceed the welding force between the upper contact holding member 3 and the lower contact holding member 4, and this has led to the problem that the welding work becomes difficult or the welded portions are peeled by a change with time. If the welded portions are peeled during photographing, unsatisfactory conduction will take place and the giving and receiving of an electrical signal will become impossible, and automatic exposure control and automatic focus adjustment will become impossible. Also, when the camera is to be repaired, there will be no alternative but to interchange the entire electrical connector, and since electric circuit parts are usually soldered to the lens side FPC 6, the repair will become costly.